Molecular Insights into the Structure and Property Variation of the Pressure-Induced Solid Electrolyte Interphase on a Lithium Metal Anode

Solid electrolyte interphase (SEI) is regarded as the key to developing stable and long-cycling lithium metal batteries (LMBs). The inevitable stress caused by the Li-metal anode expansion/contraction and the battery encapsulation is crucial to the SEI growth and properties. Herein, we perform reactive force field (ReaxFF) molecular dynamics simulations to investigate the structure and property variation of the pressure-induced SEI. The pressure boosts the SEI structure delamination and reduces the porosity based on the quantitative analysis of the charge spectrum and porous structure, which contributes to the formation of a thin and dense SEI. Meanwhile, the phase diagram combined with the pressure and salt concentration effects is established to obtain the proper trade-off between SEI mechanical and transport properties, demonstrating that the Li+ diffusion coefficients of the pressure-induced SEI can be improved by the high salt concentration when Young's modulus increases at the same time. The findings not only provide molecular insights into the SEI structure variation but also offer guidance and directions for optimizing the pressure-induced SEI property toward high-performance LMBs.

Automated summary

This study investigates the structure and property variation of pressure-induced solid electrolyte interphase (SEI) using molecular dynamics simulations. The results show that pressure promotes SEI structure delamination and reduces porosity, leading to the formation of a thin and dense SEI. Furthermore, the study establishes a phase diagram considering the effects of pressure and salt concentration, which provides guidance for optimizing the mechanical and transport properties of pressure-induced SEI for high-performance lithium metal batteries (LMBs).